Untypeable Haskell 98
Revision as of 00:40, 29 August 2006 by NeilMitchell (talk | contribs)
module Test where
f :: a -> a
f x = g x
where
-- g :: a -> a
g y = bind x y
bind :: a -> a -> a
bind a b = a
The above Haskell code is Haskell 98, rank-1 types, but cannot be given a type signature. Try commenting out the type signature for g and everything will go wrong.
In GHC making the type of f :: forall a . a -> a, and adding -fglasgow-exts will make this code work. No such luck in Hugs.